armpit fart

(slang) A simulation of the sound of flatulence made by creating a pocket of air between the armpit of a partially raised arm and the hand, and then swiftly closing this pocket by bringing the arm close to the torso.

Here are a few suggestions: The Classic Armpit Fart: Put the open palm of your right hand under your left armpit. Cup the hand slightly. Now flap your left arm up and down, and squeeze the air, and fart noises, out from under your palm.